"auto_nodetitle" is a small and efficient module that allows hiding of the content title field in the form. To prevent empty content title fields one can configure it to generate the title by a given pattern.
When the token module is installed it's possible to use various node data for the
auto generated title - e.g. use the text of a CCK field (since 5.x).
Advanced users can also provide some PHP code, that is used for automatically generating an appropriate title.